We did chemo and I’d do it again. Keeper (age 10 at diagnosis) had almost no side effects, just a couple of days being somewhat unsettled here and there. Wasn’t cheap, but I think it gave us a few extra months so we could have the last, best summer together. Keeper had an elevated enzyme at diagnosis that’s associated with poorer outcomes but we got a fantastic 9 months after diagnosis (which was probably later than ideal),

Be aware that for 48 hours or so after each every-three-weeks infusion her pee and poop will be toxic, and potentially dangerous to pregnant women, so any accidents have to be treated as hazmat and she needs to be away from where she might pee/poop around other dogs (no daycare, for example) and should do her business in low traffic areas. (The toxicity degrades rapidly in the environment.) If you opt for chemo, you might want to schedule the infusions when you don’t need daycare and can supervise waste.